The present invention relates to an apparatus using optical deflection.
1. Yao Li, Dao Yang Chen, Lina Yang and Robert R. Alfano, Opt. Lett. 16, 438 (1991). PA0 2. Robert R. Alfano, Yao Li, and P. Baldeck, U.S. Pat. No. 5,126,874 (1992).
As used herein the term "All Optical Streak Camera" refers to a streak camera for measuring an optical pulse without converting the optical pulse to a temporal electron signal.
Ultrashort laser pulses play an important role in ultrafast optical computing, optical signal processing, and optical communications. In these applications, the temporal profiles and the spectra of the ultrashort optical pulses usually carry the information to be investigated. One of the fundamental problems is to measure the temporal distribution of an optical pulse. Conventionally, an optical pulse is measured with a photomultiplier tube (PMT) or a streak camera. A PMT is a vacuum tube which converts an optical photon signal to an electron signal. The electron signal is processed. A streak camera is a time-to-space converter for optical pulses. The optical pulse to be measured is first convened to temporal electron signals. The electron signal is then converted into a spatial distribution hits a phosphor screen to produce a spatial fluorescence and detected by a two dimensional detector array. In the above methods, the optical pulses are all first converted into electron signal and then processed and analyzed. Hence, the speed of the measurements are significantly reduced. To increase the speed of the measurement, new methods of a direct quasi-all optical signal measurement are needed to digitize a signal.
It has been established that in a mutually perpendicular interaction geometry inside a nonlinear optical material, a probe pulse, which passes through an induced temporal prism formed by an area modulated optical pump pulse, undergoes a spatial modulation that leads to a beam deflection. This important observation can be utilized for a future generation of high speed optical pulse measurement and opto-electronic systems in the fields of optical computation and optical communications.
We disclose here all optical streak camera, all optical oscilloscope, optical signal processing, and optical A/D converters based on all optical deflection. An ultrafast all optical deflector has been disclosed in the past. A schematic diagram of an ultrafast all optical deflector is shown in FIG. 1. 13, 15, 17 and 19 denote the third-order nonlinear optical material, the strong pump beam, the weak signal beam, respectively. The device operates as follows: The strong pump and weak signal beams enter and overlap inside the nonlinear optical material in perpendicular directions. The P beam, before entering the NOM, is area modulated. As a simple example, the modulated area is taken as a triangle. The pump beam's optical power (E.sup.2) is used to induce an index of refraction change .DELTA.n=n.sub.2 &lt;E.sup.2 &gt;, where n.sub.2 denotes the nonlinear index coefficient of the material. This induced refractive index change cause an induced transient prism of a modulated shape. In this case, the signal beam, as it passes through the induced prism, will undergo a direction change. An induced transient deflection occurs. The deflection angle .gamma. can be calculated to be ##EQU1## where L and D are the triangle's base and height, respectively.